Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

412
FXUS63 KLOT 290536
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1236 AM CDT Wed Apr 29 2026

.KEY MESSAGES...

- A cooler and generally drier pattern will continue through
  early May.

- Frost may impact sensitive vegetation Friday night into early
  Saturday morning.

&&

.DISCUSSION...
Issued at 254 PM CDT Tue Apr 28 2026

Tonight, an upper-level short-wave will propagate through the
Ohio Valley. Occasional flares of frontogenesis interacting with
the baroclinic zone across the region will support isolated to
scattered showers through the overnight hours. Residual dry
low-level air may act to limit the overall duration and
footprint of showers. As a possible exception in this regard, a
more focused corridor of rain may develop near and south of a
Fairbury IL to Rensselaer IN line, where PoPs peak in the
50-60% range. Overnight lows will fall into the 40s area wide.

Some of the shower (or spotty sprinkles) activity associated
with the departing short-wave may linger over the eastern half
or quarter of the area beyond daybreak Wednesday morning. On
Wednesday afternoon, a camp of model guidance continues to
advertise broad low-level convergence near the Lake Michigan
shoreline (almost an inverted low-level trough-like structure).
As a result, spotty showers may overstay their welcome across
portions of northeast Illinois and northwest Indiana through
early to perhaps mid afternoon. The lake shadow propagating
inland with the lake breeze should result in shower activity
being scoured away from the immediate shore with time. All in
all, much lower column moisture will keep rainfall amounts light
between tonight and Wednesday.

Decreasing cloud cover through the remainder of Wednesday afternoon
should allow an opportunity for highs to warm toward 60 degrees
inland, with cooler conditions near Lake Michigan due to
onshore flow. Wednesday night looks relatively cool as surface
ridging and clearing skies sets the stage for overnight lows in
the upper 30s to lower 40s.

Broad mid and upper-level troughing will establish over
northeastern North America the rest of this week and beyond,
keeping the pattern locally fairly status quo (relatively cool
and much less stormy). The occasional passage of short-waves in
cyclonic flow will support a few more shower opportunities at
times, particularly early next work week. The coolest day of
the pattern looks to be Friday in the wake of an upper-level
shortwave anchored to a pool of cooler 850mb temperatures,
leading to highs only in the upper 40s to mid 50s (coolest near
Lake Michigan). Friday night hence looks to be a standout for
frost potential as a surface high moves into the region allowing
for calm winds and overnight temperatures in the low to mid
30s outside of the Chicago urban core. At least some moderation
in temperatures may occur by the weekend as the aggregate
upper-level troughing drifts eastward.

Castro/Borchardt

&&

.AVIATION /06Z TAFS THROUGH 12Z THURSDAY/...
Issued at 1236 AM CDT Wed Apr 29 2026

Forecast concerns include...

Chance of showers overnight and again this afternoon.
Wind directions through mid afternoon.

Scattered showers will be possible early this morning with the
bulk of this activity remaining just south of the terminals.
There will be another chance of showers this afternoon that
may eventually need prob/tempo mention with later forecasts.

Winds are expected to favor a north/northwest direction early
this morning and then more northerly around/after daybreak,
eventually shifting northeasterly with a lake breeze boundary
this afternoon. Previous wind trends look reasonable and made no
changes. However, only medium confidence regarding which side of
north winds will favor at ORD/MDW through early afternoon. cms

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

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